A method for preparing yttrium-doped zirconium oxide hollow particles

Abstract

The invention discloses a method for preparing yttrium-doped zirconia hollow particles, belonging to the technical field of thermal insulation coatings and lightweight composite materials. The method comprises the following steps: S1 yttrium powder and zirconia powder are mixed and granulated to obtain yttrium and zirconia mixed powder granules; S2 the granulated yttrium and zirconia mixed powder granules are sent into thermal plasma for oxidation sintering to form yttrium-doped zirconia hollow particles; S3 the yttrium-doped zirconia hollow particles enter the product collection system under gas transportation. The invention combines the transient high-temperature process of thermal plasma with metal oxidation combustion. The added metal yttrium is oxidized and burned in a micro-region, providing a micro-region high-temperature environment, which is conducive to the solid solution of yttrium; the micro-region heat release is organically combined with the plasma heat to promote the sintering and densification of zirconia. The micro-region oxidation combustion helps to quickly realize the surface densification of the agglomerate particles and provide a closed surface for forming a hollow structure; the internal micro-region oxidation combustion helps to densify the interior and improve the strength of the hollow particles.

Description

Technical Field

[0001] The invention belongs to the technical field of heat-insulating coatings and lightweight composite materials, and relates to a method for preparing yttrium-doped zirconia hollow particles. Background Art

[0002] The hollow structure of hollow ceramic microspheres makes them have the characteristics of low density, low thermal conductivity, sound insulation, strong electrical insulation and good thermal stability. They are a new type of lightweight industrial basic material, widely used in aerospace, petrochemical, building materials and other fields. Among the numerous hollow ceramic microspheres, hollow zirconia microspheres take into account the advantages of hollow structural materials and zirconia's low thermal conductivity, ablation resistance, and chemical corrosion resistance, and are one of the best raw materials for preparing thermal insulation materials. There are many methods for preparing hollow zirconia ceramic microspheres, mainly including template method, solvent thermal method, spray drying method and plasma sintering method.

[0003] The template method uses a pre-prepared template as the core to synthesize hollow particles; the preparation of hollow particles by solvent thermal, spray drying and plasma sintering methods abandons the use of templates as substrates. They mainly use the Ostwald ripening process to regulate the hollow structure. 2 hollow spheres [C] / / 7th China International Conference on High-Performance Ceramics (CICC 7). 2011, Xiamen, China] Using carbonaceous polysaccharide microspheres as hard templates, heterogeneous nucleation and encapsulation technology was used to successfully prepare ZrO with a particle size of 2 μm and a wall thickness of about 100 nm. 2 Hollow microspheres. Reference 2 [Guo C, Hu P, Yu L, et al. Synthesis and characterization of ZrO 2 hollow spheres [J]. Materials Letters, 2009, 63(12): 1013-1015.] ZrO with controllable shell structure was prepared using colloidal carbon spheres as templates. 2Hollow particles. Reference 3 [Ge S, Zhu W, Shao Q. Fabrication and characterization of hollow zirconia microspheres using calcium carbonate as template [J]. Zeitschrift für Physikalische Chemie, 2016, 230(11): 1617-1628.] Using CaCO 3 As a template, ZrO with a particle size of 1 μm and a wall thickness of 20 nm was successfully prepared by precipitation method. 2 Hollow microspheres.

[0004] Spray drying is an important method for preparing agglomerated particles. It uses an appropriate organic binder to aggregate different small particles and then obtains particle agglomerates from the slurry through drying. The slurry undergoes rapid heat and mass transfer during the drying process, and depending on the operating parameters and slurry properties, spherical or other shaped particle agglomerates such as hollow, dense, porous, etc. are obtained. Reference 4 [Loghman-Estarki MR, Edris H, Razavi RS, et al. Spraydrying of nanometric SYSZ powders to obtain plasma sprayable nanostructuredgranules [J]. Ceramics International, 2013, 39(8): 9447-9457.] firstly prepared YZ particles with a size of 30-50 nm by a wet chemical method. 2 O 3 and Sc 2 O 3 Co-doped ZrO 2 Nanoparticles (SYSZ), then, the slurry required for spraying is obtained by ball milling, and finally, agglomerated particles are obtained through a spray drying process, some of which are hollow particles.

[0005] The plasma sintering method uses plasma as a heat source to sinter porous ZrO prepared by other methods. 2A process for preparing hollow spherical particles by heat treating agglomerated powder. Reference 5 [Zhao L, Zhang Z, Duan Y, et al. Preparation of yttria-stabilized zirconia hollow sphere with reduced shell thickness by controlling ambient temperature during plasma process [J]. Coatings, 2018, 8(7): 245.] YSZ agglomerated powder obtained by spray drying was used as raw material, and YSZ hollow particles with a wall thickness of 3 μm were prepared by plasma sintering. Reference 6 [Qiu J, Yu DP, Xiao Y, et al. Anovel triple-cathode plasma torch with hot-wall nozzle for YSZ sphericalthin-walled hollow-shell powder preparation [J]. Ceramics International, 2023, 49(16): 27551-27566.] used YSZ powder with a median diameter of 46.43 μm and a hollow particle ratio of less than 10% as raw material and prepared it by triple cathode plasma torch sintering to obtain a tetragonal YSZ powder with a spheroidization rate of nearly 100%, a particle median diameter of 52.38 μm, a hollow particle ratio of 93.4% and an average wall thickness of only 3.63 μm.

[0006] Invention patent application CN202011114848 discloses a method for preparing spherical hollow zirconia thermal spray powder, wherein yttria-stabilized zirconia raw material is prepared into slurry; the slurry is spray-dried into balls, and high-temperature calcination is performed to remove binders and increase the bonding strength of the powder; then the calcined spherical yttria-stabilized zirconia powder is prepared into hollow balls by thermal spraying. Invention patent application CN202010941543 discloses a method for preparing hollow zirconia powder for thermal barrier coating, wherein graphite powder and zirconia powder of different particle sizes are dried and added with adhesive to form mixed particles with good fluidity and uniform particles. Then, the mixed particles are treated with a plasma spheroidizing device to melt the zirconia shell to form spherical particles with a graphite core of the zirconia shell. Finally, the spherical particles in the previous step are heated in a vacuum heating furnace and a certain amount of oxygen is introduced to react with the oxygen and graphite to generate carbon dioxide, remove the graphite in the sphere, and leave the zirconia shell to form hollow zirconia powder. Invention patent application CN201810452334 discloses a method for preparing a high temperature resistant hollow zirconia porous insulation board. Zirconium nitrate, lanthanum nitrate, yttrium nitrate, nitric acid and ethylene glycol are mixed and stirred into a clear solution; then, the clear solution is placed in a reactor for hydrothermal reaction, and the white precipitate produced after the hydrothermal reaction is dried and calcined to obtain a high temperature resistant hollow zirconia. Invention patent application CN201310043644 controls 3Y-ZrO 2The monoclinic phase properties of the powder, and the content of Al2O3% in the powder are controlled, and micron-sized hollow zirconia balls can be obtained through spray granulation, classification, and two calcinations. The authorized invention patent CN201010578575 we applied for firstly mixes the inorganic oxide raw material, solvent and adhesive additive in a weight ratio of 75-95:10-500:5-25, and then pumps them into a spray dryer for spray granulation to obtain the hollow inorganic oxide spherical precursor of the hollow inorganic oxide microspheres; finally, the obtained hollow inorganic oxide spherical precursor is subjected to high temperature instantaneous sintering to obtain low-density hollow inorganic oxide microspheres with a compressive strength of 30-150Mpa. Invention patent application CN201911389311 discloses a method and device for preparing large-particle-size thin-walled hollow spherical zirconium oxide powder. The dried zirconium oxide powder is fed into the plasma flame flow ejected by a plasma spray gun through a powder feeder. The powder melts to form a molten droplet and moves downward along the powder conveying channel. The temperature in the powder conveying channel is controlled to obtain a large-particle-size thin-walled hollow spherical zirconium oxide powder in a powder collector. The temperature in the powder conveying channel between the plasma spray gun and the powder collector is controlled by a temperature control unit. A new temperature field is formed between the plasma spray gun, the powder conveying channel and the powder collector. The temperature field can make the zirconium oxide powder completely melted during the plasma spheroidization process to form a hollow molten droplet and fully expand. The molten droplet gradually solidifies during the flight and is collected by the powder collector, thereby obtaining a hollow spheroidized zirconium oxide powder with a large particle size and a thin shell. Authorized invention patent CN200810224309 discloses a method for preparing hollow spherical nanostructured yttria-stabilized zirconia powder, which uses amorphous yttria-stabilized zirconia powder with an amorphous phase structure as raw material, and prepares hollow spherical nanostructured yttria-stabilized zirconia powder by ultra-long distance plasma flame heating, water cooling collection, and low-temperature drying. Invention patent application CN202210094168 transports porous γ-alumina powder to the plasma flame of a plasma reactor through a carrier gas for reaction, thereby obtaining hollow alumina balls, wherein the carrier gas is a mixed gas of at least one of hydrogen, oxygen, and nitrogen and argon, and the power of the plasma reactor is ≥9.75KW. Invention patent application CN201310277795 discloses a chemical preparation method for spherical hollow alumina powder for flame fusion gem production, wherein an aluminum sulfate solution is first prepared, and then a spherical aluminum hydroxide colloid coated with carbon balls is prepared by chemical precipitation, and finally, the aluminum hydroxide colloid is calcined to obtain hollow alumina.Authorized invention patent CN201310191350 discloses a method for preparing hollow silica microspheres by spray drying, wherein nano silica powder is evenly dispersed in deionized water using ammonia water, and then spray dried in a spray dryer; the droplets are atomized under the action of compressed air, and rapidly dried at above 100°C to form hollow microspheres; and then calcined at high temperature to obtain a powder with a certain strength; the microsphere particle size is 1.3 to 20.3 μm, the hollow pore size is 0.5 to 15.7, and the volume hollow ratio is 6 to 46%.

[0007] Although there are many methods to prepare zirconia-based hollow particles, most of these methods are based on templates and high-temperature sintering hollowing. However, it is difficult to form a closed hollow structure using the template method, and the template selection will limit the choice of hollow particle system. Although hollow zirconia particles can be obtained by plasma high-temperature sintering technology, plasma high-temperature sintering has more stringent requirements on the zirconia agglomerate precursor, and the transient high-temperature sintering process often makes the internal sintering density of the particles not high, and the strength of the hollow particles needs to be improved. Therefore, the development of high-strength yttrium-doped zirconia hollow particles that can be mass-produced is very important for promoting the development of thermal insulation and lightweight composite materials. Summary of the invention

[0008] The present invention proposes to use thermal plasma technology to organically combine metal oxidation combustion with plasma transient high-temperature sintering, which is helpful to realize the solid solution of yttrium oxide in zirconium oxide to form yttrium-stabilized zirconium oxide powder. At the same time, the micro-area high temperature provided by the oxidation process can make the agglomerated granulated zirconium oxide surface that is difficult to sinter rapidly sinter and densify, providing favorable conditions for forming a hollow structure, and realizing the integration of solid solution, sintering and hollow particles. Thermal plasma technology has the characteristics of high energy density, high temperature, and fast cooling rate. The reaction product has a short residence time in the plasma flame, which can effectively realize the sintering of the particle surface, providing a basis for the hollowing of particles. The sintered dense surface can provide a closed space for the internal gas expansion to create favorable conditions, so that the oxidation combustion in the micro-area further promotes the internal particle densification and the rapid expansion of gas to form high-strength hollow particles. Moreover, thermal plasma works near normal pressure, is easy to be continuous and scaled, and can realize large-scale preparation of yttrium-stabilized zirconia hollow particles.

[0009] The object of the present invention is to provide a method for preparing yttrium-doped zirconia hollow particles, which utilizes a thermal plasma transient high temperature process combined with metal oxidation combustion, and provides a micro-area high temperature environment by oxidizing and burning the added metal yttrium in a micro-area, which helps to achieve the solid solution of yttrium. At the same time, the micro-area heat release is organically combined with the plasma heat, which promotes the sintering and densification of zirconia, and in particular, the micro-area oxidation combustion helps to quickly achieve the surface densification of the agglomerate particles, providing a closed surface for forming a hollow structure. In addition, the internal micro-area oxidation combustion helps to improve the internal densification and improve the strength of the hollow particles. To achieve the above purpose, the present invention adopts the following technical solutions.

[0010] A method for preparing yttrium-doped zirconia hollow particles, characterized in that it comprises the following steps:

[0011] S1 Yttrium powder and zirconium oxide powder are mixed and granulated. First, the yttrium powder and zirconium oxide powder are respectively ball-milled to obtain raw materials of suitable particle size. Then, the two powders are wet-mixed and ball-milled to obtain a uniformly dispersed slurry. Finally, a spray granulator is used to spray granulate the mixed slurry to obtain yttrium and zirconium oxide mixed powder granules.

[0012] S2: the granulated yttrium and zirconium oxide mixed powder is sent into the hot plasma for oxidation sintering. The metal yttrium in the mixed powder reacts with the oxygen in the plasma to form yttrium oxide, and heat is released at the same time, providing reaction heat for the yttrium oxide to be dissolved into the zirconium oxide. Under the combined action of the reactor space heat provided by the plasma and the micro-area reaction heat provided by the yttrium oxidation, the yttrium is dissolved and the zirconium oxide is sintered to form yttrium-doped zirconium oxide hollow particles.

[0013] S3 yttrium-doped zirconia hollow particles enter the product collection system under gas transport.

[0014] Furthermore, the particle size of the raw material yttrium powder and zirconium oxide powder in step S1 is less than 1 μm, preferably less than 0.5 μm. The coarse raw material yttrium powder and zirconium oxide powder can be obtained by ball milling and other processes to obtain raw materials that meet the particle size requirements.

[0015] Furthermore, in step S1, the mass ratio of the raw material yttrium powder to the zirconium oxide powder is 1:100 to 8:100.

[0016] Furthermore, the solid content mass ratio of the spray granulation slurry in step S1 is 5-50%, preferably 10-30%.

[0017] Furthermore, the particle size of the yttrium and zirconium oxide mixed powder granules in step S1 is 5-150 μm, preferably 30-75 μm.

[0018] Furthermore, in step S2, oxidative sintering is performed in the thermal plasma. First, a thermal plasma generating device generates a stable thermal plasma arc. Then, the granulated material is transported to the thermal plasma arc through a feeding gun by a carrier gas for oxidative sintering.

[0019] Furthermore, in step S2, the yttrium and zirconium oxide mixed powder granules are introduced into the plasma arc through the center of the plasma arc, and the granules entering the plasma arc are 1-50 g / min per kilowatt of plasma power.

[0020] Furthermore, in step S2, a quenching gas is introduced at the lower end of the plasma arc tail flame to control the reaction temperature field. The quenching gas is oxygen with a flow rate of 0-10m 3 / h.

[0021] Furthermore, the yttrium powder in step S1 is replaced with a mixed powder of yttrium powder and yttrium oxide powder, and the mass ratio of yttrium powder to yttrium oxide powder is 1:3 to 3:1.

[0022] The yttrium-doped zirconia hollow particles obtained by the above method can be used for spraying thermal insulation coatings to obtain coatings with excellent thermal insulation and thermal shock performance.

[0023] The present invention has the following beneficial technical effects: metal oxidation is extended to micro-combustion reaction, and organically combined with plasma high temperature. Thermal plasma technology has the characteristics of high energy density, high temperature, and fast cooling rate. The reactants have a short residence time in the plasma flame, which can effectively avoid the agglomeration of particles during high-temperature sintering and densification; and the micro-combustion reaction not only strengthens the plasma high temperature to achieve solid solution of yttrium and zirconia, but also helps to improve the sintering and densification of agglomerated particles in the plasma, especially the rapid surface densification plays an important role in the formation of hollow particles. The metal micro-area oxidation combustion reaction can promote rapid surface densification. At the same time, the internal oxidation combustion has a promoting effect on strengthening the shell strength of hollow particles. Thermal plasma works at near normal pressure, is easy to be continuous and scaled, and can prepare yttrium-doped zirconia hollow particles on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 and Figure 2 This is a scanning electron microscope (SEM) photograph of the yttria-doped zirconia hollow particles obtained in Example 1.

[0025] Figure 3 This is the X-ray diffraction (XRD) spectrum of the yttria-doped zirconia hollow particles obtained in Example 1.

[0026] Figure 4 This is a scanning electron microscope (SEM) photograph of the yttria-doped zirconia hollow particles obtained in Example 2.

[0027] Figure 5 This is a scanning electron microscope (SEM) photograph of the yttria-doped zirconia hollow particles obtained in Example 3. Implementation

[0028] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings of the specification. Obviously, the described implementation is only a part of the implementation of the present invention, not all of the implementations. Based on the implementation of the present invention, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0029] Step 1) Preparation of spray granulation agglomerates: The raw material zirconium oxide is a commercial powder with a particle size of 1-5 μm, and the raw material metal yttrium powder is a commercial powder with a particle size of 10-20 μm. Take 460g of zirconium oxide powder, 31.50g of metal yttrium powder, and the yttrium oxide content is 8wt%, add 2000g of water, mechanically ball mill and mix for 8 hours, add 2.5g of polyvinyl alcohol binder, and obtain yttrium-zirconia mixed slurry after ball milling, and the slurry solid content is 19.80%. Use a spray granulator for spray granulation to obtain 15-100μm spherical particles.

[0030] Step 2) Preparation of yttria-doped zirconia hollow particles: A 30 kW thermal plasma device is used, which mainly includes a 30 kW thermal plasma generation system, a feeding system, a reactor system, a gas distribution and control system, a product collection system and an exhaust gas emission system. The central gas and the side gas argon are introduced into the plasma lamp, and the arc is ignited to form a stable plasma arc. After 3 minutes of stable operation, oxygen is added through the side gas, and the oxygen flow rate is 50L / min. Then, the spray granulation material is evenly fed into the feeding gun through the feeder. With the assistance of the carrier gas argon, the spray granulation material enters the plasma arc from the feeding gun, and the feeding rate is 10g / min. After stopping the feeding, the arc is extinguished, and the yttria-doped zirconia hollow particles are collected. The particle size of the particles is 50-100μm and the loose density is 1.8g / cm 3 .

[0031] Characterization of Yttria-doped Zirconia Hollow Particles:

[0032] The yttria-doped zirconia hollow particles obtained under the above conditions were examined using a Japan Electronics scanning electron microscope (JSM-7001F). The results are as follows: Figure 1 and Figure 2 As shown in the figure, it can be seen that the particles are regular spherical, and from a small amount of broken particles, it can be seen that the particles are hollow structures.

[0033] The composition of the yttria-doped zirconia hollow particles obtained under the above conditions was detected by Philips X'Pert PRO MPD. The results are as follows: Figure 3 shown. Example 2

[0034] Step 1) Preparation of spray granulation agglomerates: The raw material zirconium oxide is a commercial powder with a particle size of 1-5 μm, and the raw material metal yttrium powder is a commercial powder with a particle size of 10-20 μm. Take 460g of zirconium oxide powder and 31.50g of metal yttrium powder, add 4000g of water, mechanically ball mill and mix for 8 hours, add 2.5g of polyvinyl alcohol binder, and obtain yttrium-zirconia mixed slurry after ball milling, and the slurry solid content is 10.99%. Use a spray granulator for spray granulation to obtain 15-90μm spherical particles.

[0035] Step 2) Preparation of yttria-doped zirconia hollow particles: A 30 kW thermal plasma device is used, which mainly includes a 30 kW thermal plasma generation system, a feeding system, a reactor system, a gas distribution and control system, a product collection system and an exhaust gas emission system. The central gas and the side gas argon are introduced into the plasma lamp, and the arc is ignited to form a stable plasma arc. After 3 minutes of stable operation, oxygen is added through the side gas, and the oxygen flow rate is 50L / min. Then, the spray granulation material is evenly fed into the feeding gun through the feeder. With the assistance of the carrier gas argon, the spray granulation material enters the plasma arc from the feeding gun, and the feeding rate is 10g / min. After stopping the feeding, the arc is extinguished, and the yttria-doped zirconia hollow particles are collected. The particle size of the particles is 50-90μm and the loose density is 1.7g / cm 3 The particle scanning electron microscope photo is as follows Figure 4 shown. Example 3

[0036] Step 1) Preparation of spray granulation agglomerates: The raw material zirconium oxide is a commercial powder with a particle size of 1-5 μm, and the raw material metal yttrium powder is a commercial powder with a particle size of 10-20 μm. Take 474g of zirconium oxide powder, 4.09g of metal yttrium powder, and the yttrium oxide content is 5wt%, add 4000g of water, mechanically ball mill and mix for 8 hours, add 2.5g of polyvinyl alcohol binder, and obtain yttrium-zirconia mixed slurry after ball milling, and the slurry solid content is 10.73%. Use a spray granulator for spray granulation to obtain 15-90μm spherical particles.

[0037] Step 2) Preparation of yttria-doped zirconia hollow particles: A 30 kW thermal plasma device is used, which mainly includes a 30 kW thermal plasma generation system, a feeding system, a reactor system, a gas distribution and control system, a product collection system and an exhaust gas emission system. The central gas and the side gas argon are introduced into the plasma lamp, and the arc is ignited to form a stable plasma arc. After 3 minutes of stable operation, oxygen is added through the side gas, and the oxygen flow rate is 50L / min. Then, the spray granulation material is evenly fed into the feeding gun through the feeder. With the assistance of the carrier gas argon, the spray granulation material enters the plasma arc from the feeding gun, and the feeding rate is 10g / min. After stopping the feeding, the arc is extinguished, and the yttria-doped zirconia hollow particles are collected. The particle size is 50-90μm and the loose density is 1.7g / cm 3 The particle scanning electron microscope photo is as follows Figure 5 shown. Example 4

[0038] Step 1) Preparation of spray granulation agglomerates: The raw material zirconium oxide is a commercial powder with a particle size of 1-5 μm, and the raw material metal yttrium powder is a commercial powder with a particle size of 10-20 μm. Take 460g of zirconium oxide powder and 31.50g of metal yttrium powder, add 2000g of water, mechanically ball mill and mix for 8 hours, add 2.5g of polyvinyl alcohol binder, and obtain yttrium-zirconia mixed slurry after ball milling, and the slurry solid content is 19.80%. Use a spray granulator for spray granulation to obtain 15-100μm spherical particles.

[0039] Step 2) Preparation of yttria-doped zirconia hollow particles: A 30 kW thermal plasma device is used, which mainly includes a 30 kW thermal plasma generation system, a feeding system, a reactor system, a gas distribution and control system, a product collection system and an exhaust gas emission system. The central gas and the side gas argon are introduced into the plasma lamp, and the arc is ignited to form a stable plasma arc. After 3 minutes of stable operation, oxygen is added through the side gas, and the oxygen flow rate is 20L / min. Then, the spray granulation material is evenly fed into the feeding gun through the feeder. With the assistance of the carrier gas argon, the spray granulation material enters the plasma arc from the feeding gun, and the feeding rate is 10g / min. After stopping the feeding, the arc is extinguished, and the yttria-doped zirconia hollow particles are collected. The particle size of the particles is 50-90μm and the loose density is 1.8g / cm 3 . Example 5

[0040] Step 1) Preparation of spray granulation agglomerates: The raw material zirconium oxide is a commercial powder with a particle size of 1-5 μm, and the raw material metal yttrium powder is a commercial powder with a particle size of 10-20 μm. Take 460g of zirconium oxide powder and 31.50g of metal yttrium powder, add 2000g of water, mechanically ball mill and mix for 8 hours, add 2.5g of polyvinyl alcohol binder, and obtain yttrium-zirconia mixed slurry after ball milling, and the slurry solid content is 19.80%. Use a spray granulator for spray granulation to obtain 15-100μm spherical particles.

[0041] Step 2) Preparation of yttria-doped zirconia hollow particles: A 30 kW thermal plasma device is used, which mainly includes a 30 kW thermal plasma generation system, a feeding system, a reactor system, a gas distribution and control system, a product collection system and an exhaust gas emission system. The central gas and the side gas argon are introduced into the plasma lamp, and the arc is ignited to form a stable plasma arc. After 3 minutes of stable operation, oxygen is added through the side gas, and the oxygen flow rate is 20L / min. Then, the spray granulation material is evenly fed into the feeding gun through the feeder. With the assistance of the carrier gas argon, the spray granulation material enters the plasma arc from the feeding gun, and the feeding rate is 30g / min. After stopping the feeding, the arc is extinguished, and the yttria-doped zirconia hollow particles are collected. The particle size of the particles is 50-100μm and the loose density is 1.9g / cm 3 . Example 6

[0042] In this embodiment, the yttrium powder is replaced by a mixed powder of yttrium powder and yttrium oxide powder.

[0043] Step 1) Preparation of spray granulation agglomerates: The raw material zirconium oxide is a commercial powder with a particle size of 1-5 μm, and the raw material metal yttrium powder is a commercial powder with a particle size of 10-20 μm. Take 474g of zirconium oxide powder, 2.5g of yttrium oxide powder, 2.05g of metal yttrium powder, and the yttrium oxide content is 5wt%, add 2000g of water, mechanically ball mill and mix for 8 hours, add 2.5g of polyvinyl alcohol binder, and obtain yttrium-zirconia mixed slurry after ball milling, and the slurry solid content is 19.80%. Use a spray granulator for spray granulation to obtain 15-100μm spherical particles.

[0044] Step 2) Preparation of yttria-doped zirconia hollow particles: A 30 kW thermal plasma device is used, which mainly includes a 30 kW thermal plasma generation system, a feeding system, a reactor system, a gas distribution and control system, a product collection system and an exhaust gas emission system. The central gas and the side gas argon are introduced into the plasma lamp, and the arc is ignited to form a stable plasma arc. After 3 minutes of stable operation, oxygen is added through the side gas, and the oxygen flow rate is 20L / min. Then, the spray granulation material is evenly fed into the feeding gun through the feeder. With the assistance of the carrier gas argon, the spray granulation material enters the plasma arc from the feeding gun, and the feeding rate is 10g / min. After stopping the feeding, the arc is extinguished, and the yttria-doped zirconia hollow particles are collected. The particle size of the particles is 50-110μm and the loose density is 1.9g / cm 3 .

[0045] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The protection scope of the present invention is defined by the claims and their equivalent technical solutions.

Claims

1. A method for preparing yttrium-doped zirconia hollow particles, characterized in that: The following steps are involved: S1 Yttrium powder and zirconium oxide powder are mixed and granulated. First, the yttrium powder and zirconium oxide powder are respectively ball-milled to obtain raw materials of suitable particle size. Then, the two powders are wet-mixed and ball-milled to obtain a uniformly dispersed slurry. Finally, a spray granulator is used to spray granulate the mixed slurry to obtain yttrium and zirconium oxide mixed powder granules. S2 feeds the granulated yttrium and zirconium oxide mixed powder granules into the thermal plasma for oxidation sintering. The specific method is as follows: first, the thermal plasma generator generates a stable thermal plasma arc; then, the granules are transported to the thermal plasma arc through a feeder gun by a carrier gas for oxidation sintering; the yttrium and zirconium oxide mixed powder granules are introduced into the plasma arc through the center of the plasma arc, and the granules entering the plasma arc are 1-50 g / min per kilowatt of plasma power; The metal yttrium in the mixed powder undergoes an oxidation reaction with the oxygen in the plasma to form yttrium oxide, while releasing heat to provide reaction heat for the solid solution of yttrium oxide into zirconia. Under the combined action of the reactor space heat provided by the plasma and the micro-area reaction heat provided by yttrium oxidation, the solid solution of yttrium and the sintering of zirconia are completed to form yttrium-doped zirconia hollow particles. S3 yttrium-doped zirconia hollow particles enter the product collection system under gas transport.

2. The method according to claim 1, characterized in that The particle size of the raw material yttrium powder and zirconium oxide powder in step S1 is less than 1 μm.

3. The method according to claim 2, characterized in that The particle size of the raw material yttrium powder and zirconium oxide powder in step S1 is less than 0.5 μm.

4. The method according to claim 1, characterized in that The mass ratio of the raw material yttrium powder to the zirconium oxide powder in step S1 is 1:100 to 8:

100.

5. The method according to claim 1, characterized in that The solid content mass ratio of the spray granulation slurry in step S1 is 5-50%.

6. The method according to claim 5, characterized in that The solid content mass ratio of the spray granulation slurry in step S1 is preferably 10-30%.

7. The method according to claim 1, characterized in that The particle size of the yttrium and zirconium oxide mixed powder granules in step S1 is 5-150 μm.

8. The method according to claim 1, characterized in that The particle size of the raw material yttrium and zirconium oxide mixed powder granules in step S1 is 30-75 μm.

9. The method according to claim 1, characterized in that: In step S2, quenching gas is introduced at the lower end of the plasma arc tail flame to control the reaction temperature field. The quenching gas is oxygen with a flow rate of 0-10m 3 / h.

10. The method according to claim 1, characterized in that The yttrium powder in step S1 is replaced with a mixed powder of yttrium powder and yttrium oxide powder, and the mass ratio of yttrium powder to yttrium oxide powder is 1:3 to 3:

1.

11. Yttrium-doped zirconia hollow particles obtained according to the method described in any one of claims 1 to 10.

Images